Surgical bypass (anastomosis) of the gastroenterological (GI), vascular, or urological tracts are typically formed by cutting holes in the tracts at two locations and joining the holes with sutures or staples. The procedure is invasive, and subjects a patient to surgical risks such as bleeding, infection, pain, and adverse reaction to anesthesia. Additionally, an anastomosis created with sutures or staples can be complicated by post-operative leaks and adhesions. Leaks may result in infection or sepsis, while adhesions can result in complications such as bowel strangulation and obstruction. Additionally, while traditional anastomosis procedures can be completed with an endoscope, laparoscope, or robot, it can be time consuming to join the holes in the tissues.
As an alternative to sutures or staples, surgeons can use mechanical couplings or magnets to create a compressive anastomosis between tissues. Using surgical techniques, such as endoscopy or laparoscopy, couplings or magnets are placed over the tissues to be joined. Because of the strong compression, the tissue trapped between the couplings or magnets is cut off from its blood supply. Under these conditions, the tissue becomes necrotic and degenerates, and at the same time, new tissue grows around points of compression, i.e., on the edges of the coupling. When the coupling is removed, a healed anastomosis between the two tissues is formed.
Nonetheless, the difficulty of placing the magnets or couplings limits the locations that compressive anastomosis can be used. In most cases, the magnets or couplings have to be delivered as a completed assembly, requiring either an open surgical field or a bulky delivery device. For example, existing magnetic compression devices are limited to structures small enough to be deployed with a delivery conduit e.g., an endoscopic instrument channel or laparoscopic port. When these smaller structures are used, the formed anastomosis is small and suffers from short-term patency, typically lasting several weeks at best.
To overcome the limitations of the mechanical or magnetic coupling devices described above, researchers have developed deployable magnetic anastomosis devices that can be delivered via a delivery conduit. Upon delivery, the devices are intended to self-assemble in useful shapes to form the anastomosis. Such devices are reported in U.S. Pat. No. 8,118,821, incorporated by reference in its entirety. Unfortunately, these designs are not sufficiently robust to be adapted for human use. In some instances, the magnetic pieces become separated from the anastomosis device, creating a risk of blockage in unintended systems. In other instances, the anastomosis devices do not self-assemble correctly and require additional surgical procedures to remove the malformed device. Regardless, previous clinical trials have met with little success. See, e.g., U.S. NIH Clinical Trial NCT00487552, terminated for failure to meet a primary endpoint.
Thus, there still remains a clinical need for reliable devices and minimally-invasive procedures that facilitate compression anastomosis formation between tissues in the human body.